We've used all levels up to 11 of Developmental Mathematics after trying many other math curriculum. This style of learning is what works for my daughter who is challenged by math to a great degree. We'll likely use it for our 6 year old son. I highly recommend it for those who've "tried it all"; it's inexpensive compared to others and you're not out alot of money if it doesn't work for your child, as you can buy one level at a time. ChristianBook is one of only a few places you can find Developmental Mathematics and these prices are quite fair. We've ordered many things from ChristianBook and will continue to shop here; a very reliable store!